Which of the following correctly uses the word "affect"?

The first choice accurately uses the word "affect" in the context of this sentence. "Affect" is a verb meaning to influence something, and in this sentence, it describes how the weather has an impact on the person's mood. This aligns perfectly with the definition of "affect," as it conveys an active influence.

The other options utilize "effect," which is a noun referring to the result of a change or an action, or use "effect" as a verb in a different context. Therefore, those sentences do not feature "affect" in the way the question requires, demonstrating a different meaning and usage. In summary, the correct sentence exemplifies "affect" as an influence on an emotional state, while the alternatives discuss results or changes, which are not instances of usage for the verb "affect."